Film drying apparatus



United States Patent "ice 3,403,455 FILM DRYING APPARATUS Robert J.Wilson, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester,N.Y., a corporation of New Jersey Filed Mar. 2, 1967, Ser. No. 620,084 9Claims. (Cl. 34-159) ABSTRACT OF THE DISCLOSURE A film drier wherein asingle film strand within an easily threadable shallow channel movespast a plurality of oppositely disposed hot air jets developed in theshallow channel walls. By distributing the jets uniformly along bothsides of the channels, high-speed, efficient, drying is accomplishedwithout shoreline degradation or flutter damage of the film.

Background of the invention The present invention relates to driers andmore particularly to high-speed driers suitable for drying continuouswebs or strips.

In the art of high-speed drying of strips such as photographicfilmstrips there are several problems which require unique solutions toeffect a most satisfactory drier. One of the more popular prior art filmdriers has many coaxial conveyor rollers placed in a manner making itquite complicated to thread the film therethrough. A more acceptabledesign from a threading standpoint has hot air presented to only oneside of the film. However, in such a system, the film tends to flutterwhen the drier is operated, particularly at the higher air flow ratesnecessary for high-speed drying. This, of course, raises a problem offilm tension variation which, in an extreme case, such as a wet filmmomentarily sticking to another surface, can cause film breakage withresulting loss of time and material. Avoidance of destructive fluttercan be accomplished by use of short lengths of film between closelyspaced support rollers. However, certain driers with short film runsbetween turnaround rollers tend to develop shoreline residue damage.This damage effects a discoloration of the strip which occurs when thefilm is moved between two high-speed drying regions by means of aturn-around mechanism or a cross-over region. In the cross-over thedrying is slowed considerably. Such alternate fast and slow dryingperiods tend to create drying ridges having a visible flaw pattern thatresembles the patterns created by waves on a sandy shoreline.

Therefore, an object is to provide an improved highspeed filmstripdrying apparatus.

Summary of the invention In accordance with one embodiment of myinvention a drier segment comprises a corrugated or fluted panel havinga tortuous channel path on one side. Film support rollers are positionedat the corners of the path to convey a single web or strip of filmthrough each of the straight channel sections. The single strip depthsolves the prior art difficulty of threading the drier. Along the sidewalls of each of the channels are provided a plurality of opposedapertures or slots whereby heated air forced to fiow through the drierpanel creates hot air jets. These balanced hot jets impinge on oppositesides of the filmstrip at a plurality of closely spaced locations.Impingement of air on opposite sides of the filmstrip does away with theflutter problem. Thus, long channels may be used without excessivetension problems, and the channel pattern of the drier may be arrangedto fit almost any available space. The air flow pattern provides hot air3,403,455 Patented Oct. 1, 1968 jets along the entire length of eachchannel section and throughout the region of turn-around roller and thecrossover areas. This distribution of hot air jets throughout thetortuous channel path continuously maintains a high rate of drying sothat shoreline damage is avoided.

The subject matter which is regarded as my invention is particularlypointed out and distinctly claimed in the concluding portion of thespecification. The invention, however, as to its organization andadvantages thereof, will best be understood by reference to thefollowing description taken in connection with the accompanying drawing,in which:

FIG. 1 is a block diagram of a conventional drier layout suitable foruse with my invention;

FIG. 2 is a simplified perspective cut-away view of one conventionaldrier apparatus;

FIG. 3 is an enlarged plan view of a film segment illustrating theshoreline residue damage problem;

FIG. 4 illustrates a preferred embodiment of my invention;

FIG? 5 is a sectional view taken along the line 55 of FIG. 7;

FIG. 6 is a cut-away view taken along the line 6--6 of FIG. 5 and FIG. 7is a view of another embodiment of my invention.

Referring now to the drawing, wherein like numbers indicate similarparts, I have shown in FIG. 1 a drier 10 which receives, through a drierinput slot 12, a wet strip of material such as a 16 mm. or 35 mm.photographic filmstrip 11 from a processor. Air, indicated by the arrows14, is pumped by a blower 15 through a heater 16 to pass through thedrier 10 at a high-speed drying temperature such as F.

Certain inner parts of one of the conventional driers are indicated inthe simplified perspective cut-away view of FIG. 2. The drier has aplurality of plenum chambers 20. The front chamber 20 is indicated inphantom lines to allow a clear showing of one of the several spiralpaths of the filmstrip 11 during the period it is being hot air driedbetween the several plenum chambers 20. The filmstrip 11 is conveyed ona plurality of transport rollers 22 in a spiral path between each set ofthe plenum chambers 20 so that the emulsion side of the filmstrip (theouter side of the spiral) faces a plurality of hot air emitting slots 24to be dried rapidly.

Placing of an additional'plenum chamber within the filmstrip spiralbetween the rollers 22 could obviously increase the number of air slots24. However, such a more complex construction would seriously complicatethread ing of the filmstrip over the rollers. For instance, plenumchamber in the center of each spiral usually requires partialdismantling of the drier for threadup. Since the two plenums shown inFIG. 2 direct air toward only one (the emulsion) side of the filmstrip,flutter is a problem. Flutter is the motion of a long strip segment inresponse to air flow directed toward only one side thereof. The flutterproblem is further aggravated by the flow of the air from the center ofthe spiral toward the end thereof. Thus, the end strands of the spiralare subjected to a lateral air flow as well as the direct impingementfrom the slots 24. The distance between the upper and lower rollers 22is kept short to avoid damaging flutter. At such times as tension in thefilmstrip is momentarily relaxed long spacing tends to allow thefilmstrip to stick to itself and sometimes break. Additionally, itshould be noted that there are no air slots provided in the region ofthe outer surface of the turnaround rollers 22 nor in the cross-overregions 25 where the filmstrip 11 moves from one spiral roller group toa next.

Referring now to FIG. 3, I have shown one of the results of a filmdamage which tends to occur during the rapid drying of filmstrips 11 ina conventional drier of the FIG. 2 construction. This film damage isknown as shoreline wherein the filmstrip dries rapidly in a first regionadjacent to an edge. Then the drying is slowed in a next region, wherebya visible line is created, several being indicated at 26. This slowerdrying of the filmstrip 11 often occurs when the filmstrip is movingthrough the crossover regions 25 where the air impingement on thefilmstrip is greatly reduced, and may also occur when the film movesover the turn-around rollers 22.

Referring now to FIG. 4, I have shown an embodiment of my inventionhaving a completely different type of film path from that in the drierof FIG. 2. In my drier the filmstrip 11 is not moved through a spiralpattern but is moved through a tortuous channel path formed in thesurface of several panels 28 (by way of example, two panels beingshown). As these channels are only about one filmstrip width deep, thefilmstrip 11 may easily be threaded into a cross-over channel 29 andover one of the rotatably mounted transport rollers 22 into a muchlonger drying channel 31 to a second transport roller 22, etc. Thesechannels are perforated or slotted to allow heated air to impinge onboth sides of the filmstrip 11. Moreover, the path of the filmstrip 11(indicated in phantom) is never outside of the channels 29 or 31 duringthe drying cycle. Thus, heated air continually impinges on and dries thefilmstrip as it moves through the drier, whereby shoreline damage isgreatly reduced or eliminated compared to prior art structures.

This air impingement is better illustrated by the detail shown in FIGS.5 and 6 wherein a panel 28 is indicated in section with apertures shownas slots 35 opposed to one another (FIG. 5) so that air pressure onopposite sides of the filmstrip 11 (indicated in phantom) is equalized.With such balanced air pressure no damaging flutter is created. With noflutter problem, the channels 31 may be made as long as desired to fillany available drier space without any problem of excessive tension inthe filmstrip.

In fact when long channels are used and fewer transport rollers 22 arerequired, a lower driving force may be used with a further reduction offilm tension. Also, balanced air impingement will provide a cushion orlubricant to prevent the filmstrip being driven against and sticking toa wall surface of the long channel 31. Moreover, the filmstrip is not ina position to stick to itself as it could with a drier of the FIG. 2construction. Thus, momentary sticking is prevented, and this cause offilm breakage is eliminated.

FIGS. 5 and 6 also showv a portion of the open support frame, in theform of a strut member 38, to which the panel 28 is bolted. With airpumped toward one side of the panels 28, their many slots 35 operate todevelop air jets directed toward the film in a manner more effectivethan the slots 24 of the plenum chambers in FIG. 2, because each slot isused for directing air to a single strand of film. Thus every slot maybe of a simple design and yet most efiicient and effective size anddesign compared to the slots 24 which must supply air to severalfilmstrip sections.

FIG. 6 shows the slots 35 being substantially equally spaced throughoutthe length of the channel section. Similar spacing is providedthroughout the outer surface of the short cross-over channels 29 as wellas around the outer surface of the rollers 22. Additionally, at leastone hot air slot is provided at a channel wall tip 39 between therollers 22. Thus, drying of the filmstrip 11 is not materially sloweddown even in the cross-over region of channel 29. The rollers of theFIG. 4 construction do not turn the filmstrip more than about 90",whereby less relative time elapses between hot air impingement dryingperiods even on the inner surface of the filmstrip. Finally, the rollers22 may be made as small as hot (140 F.) film bending limitations willallow, because the roller size is Cir no longer the determinativeelement in the spacing between the filmstrips as compared to the FIG. 2drier construction.

Because of the low tension needed to transport the film with no flutterand because of long unobstructed runs, it is not necessary to drive allof the rollers 22. In fact, some of the time it is not necessary topower all of the several driving rollers provided. Therefore, a tendencydrive roller 40 is positioned to drive one of the transport rollers 22in each of the panels 28, whenever the film strip is tensionedsufficiently to press the roller 22 against it. As several acceptabletendency or take-up drives are known, such as that shown in Patent3,132,574 Ernisse issued May 12, 1964, it is not necessary to set forthsuch a one way drive mechanism in great detail here.

FIG. 4 also shows the left side of the left (input) panel 28 as having abafile member or block 41 positioned against the apertures 35 of thehalf channel which does not contain any film. The use of such a blockreduces the wasted hot air fiow through the panels 28. A similar blockmay be positioned inside the right hand panel 28 topre vent some of theair flow through the last half channel" 31 also. In the channelarrangement of FIG. 4 about 25% to 35% of the panel surface is taken upby the tortuous channel path (29, 31).

Referring now to FIG. 7 a somewhat more efficient space utilizingembodiment of my invention is illustrated wherein about of the surfaceof panel 28a is recessed in the form of channels. In this construction,the filmstrip 11 is moved through channels 29a and 31a of the panel 28aand six transport rollers 22 are provided instead of the four transportrollers of the panel 28. Again, the crossover and turn-around regionsare provided with slots 35 both at the outer side of the film and at theinner tips 39. With filmstrips wherein shoreline is a particular problemcare should be used to be sure that each of the trans port rollers 22being driven by the tendency drive roll 40 receives the filmstrip 11 sothat the emulsion coating is outermost. Thus, the emulsion surface willbe continually bombarded by hot drying air from slots around the drivenroller.

As may be apparent to those familiar with the drying art my inventionmakes it quite practicable to provide drying chambers that are longerand thinner than those of a more conventional design. However, sincethese drying chambers of my invention are easily made of light weightmaterial, for instance, the panels 28 may simply be molded plastic andthe rest of the drier box may be relatively light weight sheet metal ortransparent plastic sheets, the overall thickness of the drier may be nomore than two or three inches greater than the width of the filmstrip.Thus, for many filmstrips the drier need be no wider than about six oreight inches.

With this construction, it is feasible to hinge the driers so that theymay easily be moved out of the way either during use or when out of use.One instance when such a foldaway hinged drier is of value is whenseveral of these processors and driers are closely positioned side byside, and it is necessary to rethread one of the driers. Obviously, allof the ones to one side of the one being rethreaded could be folded sothat the panel surface is exposed to provide substantially greateraccess than has been available for rethreading driers in the past. Witha film take-up system mounted on the hinged drier, it is not evennecessary to disturb the operation of any of the driers which are movedout of the way.

It should now be apparent that the drier of my invention is easy tothread, because it is only a single strip in' depth; that there is noflutter produced because of the balanced air jet impingement; and thatthere is no shoreline drying because of the ample and evenly spaceddistribution of hot air slots 35 throughout the drying distance. Also,the panels may be easily set up in drier strips of 2, 3, 4 panels etc.depending on particular drying capacity requirements.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention as described hereinabove and as defined in the appendedclaims.

I claim:

1. A drier for strip material including a blower situated to pump heatedair and comprising:

a panel member having on one side a tortuous channel path consisting ofcurved portions and straight portions, the channel path being of a depthless than about two widths of the strip material so that a single strandof the strip material may be effectively dried therein; and

transport rollers located at each corner portion of the tortuous channelpath for transporting the strip material within the channel path withoutits touching any channel wall surface, each channel wall being providedwith a plurality of apertures for directing streams of drying airagainst the strip material at a plurality of locations throughout thetortuous channel path, the apertures being spaced substantially uniformdistances apart throughout the tortuous channel path except where one ofsaid rollers is located between a channel wall surface and the stripmaterial, such uniform spacing providing substantially uniform drying ofat least one side of the strip material to prevent shoreline damagethereto.

2. The invention of claim 1 wherein:

said plurality of apertures are opposed through relatively long straightchannel paths to prevent flutter of the strip material between widelyspaced transport rollers.

3. The invention of claim 1 wherein:

said tortuous channel path comprises at least about 30% of the surfaceof said panel member.

4. A high-speed, hot-air drier for a photographic filmstrip, wherein ablower moves air past a heater to supply hot air impingement at thefilmstrip surface, comprising:

a panel member having a continuous and curved channel path on onesurface thereof with hot air emitting slots spaced along both opposingwalls of the channel path; and

transport rollers located at each corner of the channel path fortransporting a single filmstrip within the channel and between theopposed hot air emitting slots, said slots extending around the outerside of the curves of the channel to cause hot air jets to impingeagainst the filmstrip on said rollers so that the drying rate of thefilmstrip is maintained substantially constant to prevent shorelinedamage.

5. In a drier for photographic filmstrip having an air heater, a blowerfor moving heated air from the heater to impinge on the strip to bedried, and means for moving the strip through the drier, the improvementcomprising:

a thin wall panel member having one strip receiving channel ofsubstantial U-shaped cross section, the sides of the U being of slightlydeeper than the width of the strip and being spaced a distancesubstantially greater than the thickness of the strip;

said channel including curved and relatively straight portions arrangedto form a tortuous path for the strip and having a plurality of spacedapertures in said sides along said path for directing heated air againstthe strip surfaces; and

transport rollers mounted for rotation in the curved portions of saidchannel for guiding the moving strip through the channel out of contactwith the panel member.

6. An air drier for a moving strip, comprising:

a panel member defining one strip receiving channel having opposed sidewalls of a depth slightly greater than the width of the strip to bedried;

said channel including curved portions and being arranged to form acontinuous tortuous path for the strip;

said side walls being spaced a distance substantially greater than thethickness of the strip and having therein a plurality of spacedapertures for directing drying air against the strip as it moves throughthe channel; and

transport means mounted for rotation in the curved portions of saidchannel for guiding the strip through the channel out of contact withsaid side walls, whereby uniformity in the drying of the moving strip isenhanced.

7. The invention of claim 6 and wherein;

the apertures in one side wall of the channel are positioned insubstantially opposed relation to the apertures in the other side wallof the channel to thereby reduce flutter of the moving strip in thechannel.

8. The invention of claim 6 and wherein;

said apertures are in the form of narrow slots which are positioned insubstantially opposed relation in the side walls of the channel so as todirect streams of heated air onto the full width of the strip.

9. The invention of claim 6 and wherein;

the length of at least some straight portions of channel exceeds thelength of curved portions, and a plurality of straight portions in saidpanel member are substantially parallel.

References Cited UNITED STATES PATENTS 2,932,902 4/1960 Copenhefer 341592,920,399 1/1960 Fry 34l59 3,263,345 8/1966 Fleisher et a1. 3459 KENNETHw. SPRAGUE, Primary Examiner.

